Rubber-based propellants are typically tested for burning rate as part of quality control. This burning rate test involves the placement of a strand of the propellant in a cylindrical bomb and the ignition of the strand by a hot electrical wire. The test then records the start and stop times of the combustion of the strand over a specified distance. A burning rate may then be calculated.
Testing engineers have determined that cross-sectionally round or cylindrical strands of propellant provide better results in burning rate tests because round strands tend to combust more homogeneously from start to finish. Accordingly, engineers and technicians have sought methods for manufacturing or machining round strands of rubber-based propellants.
Related methods of machining strands of rubber-based propellants recognize safety precautions concerning the explosive nature of rubber-based propellants. These safety concerns require a technician operating a milling machine to control and observe the cutting of the propellant from a remote location. One example of remote operation involves a remotely-controlled guillotine cutter. The guillotine cutter simply cuts the soft propellant in two directions to provide a rectangularly-shaped strand. If the technician then wishes to produce a round strand, he must manually trim the corners of the rectangular strand. This method has two distinct disadvantages. First, the method requires the technician to come into physical contact with the propellant during cutting. This contact contradicts the recognized safety precautions normally followed during machining of rubber-based propellants. Second, the method includes an unautomated step of manual trimming, which increases the length of time necessary for machining a round strand.
Other cutting methods and devices of the related art include the belt skiving device of U.S. Pat. No. 4,656,910 by Peterson. Peterson discloses a device for cutting longitudinal channels or strips in the cover of a rubber conveyor belt. The device includes a U-shaped blade set at a specified angle relative to the surface of the conveyor belt. The U-shaped blade has a front portion with a sharp cutting edge. The blade cuts into the surface of the belt and removes rectangular, longitudinal strips.